The present invention concerns a computer-based system for synchronizing and controlling the operations of a glassware forming machine. The glassware forming machine includes a number of individual section (IS) machines which receive molten glass from a furnace or forehearth to be molded into a particular glassware article. The article or ware is passed by way of a transfer conveyor to a lehr for annealing the glass. The present invention thus contemplates a computer-based system for scheduling the operation of each section and its mechanical components, and for providing access by the machine operator to modify the glassware forming sequence and timing of events.
A typical glassware forming machine includes a plurality of sections which are each capable of manufacturing glassware by itself. The sections are operated in synchronism according to a particular phase relationship between each section in order to permit the plurality of sections to obtain gobs of molten glass from a single source in an ordered sequence. Each section then forms these acquired gobs of molten glass into a number of finished glassware articles which are then delivered to an output conveyor, again in synchronized fashion. While one section is delivering glassware to the conveyor, another section may be engaged in a different step in the formation of the glassware article. When properly timed and phased, wholly formed glassware articles are produced by each section and passed in an orderly fashion onto the conveyor which transports the glassware articles to a stacker, and ultimately to lehr for annealing.
The glassware forming machine, and each section includes a number of functional components or mechanical devices which perform each of the steps in the glassware forming operation. For instance, the machine includes a feeder for acquiring molten glass from the forehearth and passing the molten glass to a gob distributor. A shear cuts the molten glass into measured gobs. The gob distributor includes a number of scoops which are used to convey the measured gobs to one of the number of sections associated with the gob distributor. Separate motors are used to drive the feeder, shear and gob distributor.
Each section also includes a number of mechanical devices which can be pneumatically, hydraulically or electrically controlled. For instance, each section receives the molten glass and includes a component for molding the glass, or blowing the glass, into a glassware article. The glassware article is typically formed in a section and then transferred to dead plate which can include the component for blowing cooling air onto the glassware article. A pusher assembly is used to push the glassware article from the deadplate onto a moving conveyor adjacent the IS machine. Each sections may include means for forming more than one glassware article. Thus, the pusher may also include a number of arms for simultaneously pushing the number of glassware articles from the deadplate onto the conveyor in unison. Each of the mechanical devices of the IS machine is typically commanded by a valve block which signals the operation of each of the components in an appropriate timed sequence.
In a typical glassware forming machine, multiple sections feed glassware articles onto a common conveyor. Each of the sections may produce up to four articles of glassware at a time. Thus, throughout a single cycle of the glassware forming system, multiple glassware articles can be produced by the totality of the IS machine. These glassware articles mush be properly formed and properly passed to the conveyor so that no conflict results--that is, so that glassware articles do not crash into each other as they enter the transport conveyor. The operation of the glassware forming system requires precise timing of each of the steps of the glassware forming process including formation of the molten gob, distribution of the gob to each section, formation of the glassware article at in each section, and transport of the finished article to the transfer conveyor and ultimately to the lehr.
In past years, cumbersome systems of cams, drum timers and mechanical linkages were used to provide the proper timing and sequence of events for each of the mechanical components of the glassware forming system. In recent years, however, electronic timing has replaced the prior mechanical systems, and solving many of the problems associated with those systems. Electronic timing and synchronization provides more accurate control of the glassware forming process and greater flexibility in manipulating or changing the sequence and timing of glassware forming events.
For the purposes of the following disclosure, a number of terms will be defined which are frequently used in the glassware forming art. In the art, a "shop" is a particular glassware forming machine. This glassware forming machine includes a multiple number of individual sections. A "shop cycle" is the amount of time required for a complete cycle of all events for all of the individual sections forming the shop. For convenience, and configuration purposes, a complete shop cycle has been defined in the art in terms of degrees from 0.1 to 359.9 degrees, usually in 0.1 degree increments.
An "event" is sued to designate a step in the glassware forming process. More specifically, an event is the association of a particular output to change the state of a mechanical device at a certain angle in the shop or IS machine cycle. Each event has an "on angle" and an "off angle" to designate when the particular event begins and ends. For each event, and more specifically for each particular output, a signal is sent to a device controller which is used to activate or de-activate the motors, valves, solenoids, etc., driving the actual mechanical components of the shop. Each mechanical device of every section of the shop will have an output associated with it, and the operation of each of these components will have a specific event associated with it.
Each of the IS machines is operated in a "firing order". This firing order constitutes the order in which each section receives gobs from the gob distributor. As each section is activated in the firing order sequence, each section commences operation at a different angle in the shop cycle. This angle is known as a "section differential offset" which represents the delay from the beginning of the shop cycle before the individual section begins its own glassware forming cycle. Each section also operates in a cycle from receiving the glass gob to forming the glassware article to pushing the article onto the transfer conveyor. Each section cycle has the same duration as the shop cycle so that synchronization is important between the shop and section cycles.